Confused about Differences of Watering Herbs Indoors and Out
Answered by: Richters Staff
Question from: Sara Jackson
Posted: Before April 1998

I’m a brand new subscriber to your catalog and equally new to the world of home-grown herbs. I tried rosemary and lemon basil in pots last year, but they dried up and died on me. My question: If they’re put outside to get good sunlight, must they be watered every day? Indoors I’ve killed several rosemary plants by overwatering, so I’m confused. Also, do they do better in pots outside or in the ground? I look forward to receiving your catalog and trying again this summer.

Good questions. The cultural needs of herbs do change a lot depending on whether they are grown outdoors or in. Differences in their requirements can easily confuse inexperienced gardeners.

For good growth most of the popular herbs need good light. Outdoors, it seems, a sunny location and rich, well-drained soil is all that is needed for success. In many localities receiving moderate rainfall little or no watering is necessary. It is easy to get the impression that herbs grow like weeds. Growing them indoors, it seems, must be easy too. Not true!

Amount of water needed is closely related to the amount of light plants receive. Outdoor plants receive more than 10 times the light they receive in a bright sunny window. With more light there is more heat causing more transpiration (water loss) through the leaves and more evaporation from the soil surface. But potted plants need more water than garden plants because they are more exposed to the heat and dry out more easily. Also, in-ground plants have larger root systems that can draw upon a larger reservoir water in the soil. What this means is: if you plant herbs in the garden they will require the least amount of care and watering; and if you grow potted herbs outdoors (on a patio or balcony, for example) they will need frequent watering – perhaps even several times a day depending on the heat. Planting herbs in the garden is by far the surest and easiest way to grow herbs.

Indoors, potted herbs dry out less often. With weaker light and usually cooler temperatures in the summer, they will not grow as fast and will not need to be watered as often as outdoor potted herbs. It is very easy to overwater herbs indoors, especially during the winter months when they are growing slowly or may even be dormant. Rosemary is especially prone to overwatering.

For further information consult John Steven’s "Gardening With Herbs" which has sections on growing herbs in gardens, on patios in containers, and indoors.

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